Dynamic positioning is an advanced control system that enables a vessel to maintain its exact position and heading using thrusters and propellers, without the need for anchors. This dynamic positioning system integrates GPS, wind sensors, motion sensors, and computer controls to counteract external forces like wind, waves, and current, ensuring precise station-keeping even in harsh marine environments.
This technology is essential for offshore operations, such as drilling, subsea installation, cable laying, and scientific research. A modern dynamic positioning vessel benefits from fully automated control, enhanced maneuverability, and increased operational safety and flexibility.
Dynamic Positioning offers advantages such as:
- Drillships & FPSOs – Maintain safe positions while drilling and producing.
- PSVs & AHTS Vessels – Support offshore platforms with supply and anchor handling.
- Construction & Subsea Vessels – Perform cable laying, installations, and maintenance.
- Wind Farm Installation Vessels – Deploy and service offshore turbines.
- Research Vessels – Conduct oceanographic studies with minimal disturbance.
- Cruise Ships & Ferries – Ensure safety and comfort during controlled stops or docking.
As dynamic positioning systems become the standard across offshore and naval industries, understanding their classification and capability is key to safe and efficient operation.
Dynamic Positioning Class
The dynamic positioning class defines the robustness and redundancy of the DP system on a vessel. Classification is essential to assess the level of automation and fault tolerance under failure scenarios, especially for critical missions. There are generally three classes:
- DP1: Features automatic and manual position and heading control without redundancy. A single fault can lead to loss of position. Not very common in offshore vessels. Some crew transfer vessels are within this group.
- DP2: Incorporates redundancy such that no single fault in an active (e.g., generators, thrusters, control systems, etc…) or static component will cause a loss of station-keeping. This includes failures like fire or flood in a single compartment, with the system automatically switching to its stand-by equipment without drift. This is quite common nowadays.
- DP3: Similar to Level 2 but with additional segregation of systems to withstand more severe incidents, such as fire or flood in any one compartment without loss of position. Physical separation of all systems, from generators to power buses, is a design requirement
Each classification society has its own nomenclature to describe Dynamic Positioning Class, and requirements to be considered a certain class. Keep in mind these notations are constantly updated so it’s important to always check the latest version.
Selecting the appropriate DP class is crucial during vessel design or refit to ensure compliance, reliability, and cost-effectiveness.
Dynamic Positioning Levels
In addition to class, the dynamic positioning levels describe how precisely a vessel can maintain its position against environmental forces. These levels are used to evaluate DP capability and define operational limitations for each mission profile.
The most common dynamic positioning levels include:
- Level 1: A static or quasi-static calculation designed for monohull vessel, based on static balance of sea forces against ship thrust capability. Environmental loads are simplified by guidelines and static. This level is adequate for power plant dimensioning. Is generally much more conservative in estimating external loads than higher levels
- Level 2: As per level 1, accounting for the particularities of the vessel. The analysis is quasi static. It is adequate for monohulls, semisubmersible and other offshore artifacts. Load conditions and various design margins are considered for more accurate results as compared with Level 1
- Level 3: Time domain analysis that contemplates operative constraints from the ship thrusters, ship motion, vessel time of response and environmental load oscillation.
Optionally, the environmental loads for the operational site of a vessel may be specified instead of the general ones. Choosing the right level of analysis ensures safe and optimized operation in both normal and extreme conditions, supporting confident vessel deployment.
DP Capability
DP Capability, simply put, is the weather conditions that the station keeping can withstand without loss of position after a suitable assessment level has been chosen. It normally is used along with the Beaufort scale, expressed in the maximum speed of wind withstand able.
This is normally expressed in the widely known capability plot, covering the vessel capability to withstand the sea forces in each direction of the 360º circle. The more outwards the point, the more forces it can withstand.
These plots may describe the maximum attainable with no redundancies or dynamic margin for sudden gusts, reflect the capability with a thruster or power bus failurer or other considerations. It is always important to know the context of the plot before drawing conclusions.
Other relevant data usually given is the thrust utilization plot which refers to the % of use of available thrust in order to balance fixed external loads. These plots refer to a preset wind speed.
Lastly, the station keeping circle is used in time domain simulations to keep track of how the vessels manage to react to the environment loads inside an operation area. This is used when evaluating the behavior thruster allocator and control loop of the ship computer, and also to define safety zones for restricted and non restricted DP use.
VICUSdt DP Plot Tool
VICUSdt has developed a powerful in-house DP plot tool to assess and visualize DP capability under real-world environmental scenarios. This tool integrates data from CFD simulations and environmental forces to simulate how different vessel configurations behave under station-keeping conditions. With this tool, we can:
- Compare different dynamic positioning system layouts
- Evaluate azimuth and tunnel thruster efficiency
- Analyze energy consumption for various configurations
- Optimize the vessel layout for reduced operational cost and increased safety
Our experience in vessel design and propulsion allows us to fine-tune every aspect of dynamic positioning vessel performance to meet your specific operational needs.
Real-World Application of Dynamic Positioning on Survey Vessel
Customer: GARDLINE
Related services: MANEUVERING & DYNAMIC POSITION ANALYSIS, AERODYNAMIC FORCES AND MOMENTS
This case study highlights the practical implementation of dynamic positioning technologies on a survey vessel operated by GARDLINE. The objective was to enhance DP capability through CFD simulations and system optimization, ensuring precise station-keeping in complex marine environments.
Scope of work included:
- Evaluation of vessel’s geometry and thruster layout
- CFD-based calculation of wind, current, and wave coefficients
- Force and moment analysis on each thruster
- Plotting DP capability according to environmental criteria (ENV)
- Position-keeping analysis under operational limits for a dynamic positioning vessel
Results: The evaluation allowed the team to define safe operational thresholds for the vessel while using its dynamic positioning system. The project ensured the vessel could maintain stable position and heading even under challenging environmental loads, improving mission efficiency and reliability.
